Tan Jiubin

A small probe with a gradient index lens for confocal measurement

In comparison with conventional lens, gradient index lens is lighter in weight, smaller in volume and easy to couple. In order to facilitate the measurement of a small irregular surface in a limited space, a small probe is presented, which combines the compact design of gradient index lens with the high axial resolution and absolute position tracking capability of a confocal microscope. The operating principle and construction of the measurement system are detailed. The confocal measurement system features high lateral resolution and depth-discriminated sections. The effect of various factors on axial resolution, and design of key component, such as a gradient index lens, pinhole, light source and detector are discussed. Experimental results show a axial resolution of 10 nm can be obtained when a probe of 1 mm in diameter is used to detect a slope profile of less than 20°. In addition to its application for measurement of a small irregular surface in a limited space, the sensor system proposed can be fitted onto a coordinate measuring machine for non-contact measurement of dimensions and surface roughness, and incorporated into CNC machining center for on-line quality monitoring.

Measurement Method for Micro-cavity Based on Super-resolution Restoration

One effective measurement method for micro-cavity is optical fiber micro-force contact measurement method, but the measurement precision descends because of collected blur images caused by many factors. In the paper, a method used in micro-cavity measurement based on maximum a posterior (MAP) and projection onto convex set (POCS) hybrid processing is proposed. The hybrid method dual- purposes the merit of MAP convergence and POCS edge maintenance ability, adds one convex set for every part of the image under the terms of the whole image optimum. What s more, the method can reduce the noise s effect, insure the uniqueness for optimum image, and maintain the edge information. The experiment shows that the method can be used in micro-cavity measurement, and the uncertainty of location can be improved three folds.

Superresolution character of array confocal system

For the incomplete theory of the array confocal system, the more accurate theoretical model is built, and the new type of three-zone amplitude pupil filter is presented to improve the 3D detecting ability of the array confocal system. The 3D imaging equation based on Kirchhoffs diffraction theory in the paper is more accurate, compared with the exciting theory, and it can describe the system imaging process more exactly. Using the evaluation criterion of 3D superresolution, the parameter of the filter pupil is optimized. It can reduce the axial and transversal FWHM of every detecting channel. The results of computer simulation and experiment prove that the filter can improve the axial and transversal resolution at the same time, which can increase the 3D measure capability.

Study on simulation system for 3-axis NC milling

An efficient real-time simulation system for 3-axis NC milling using microcomputers is described in this paper. In this system, the workpiece is represented with an extended Z-map structure and is displayed on screen using isometric projection. After the NC code file was generated and interpreted by an NC instruction translator, a material removal process was simulated just like that performed on real NC milling machine tools driven by NC instructions. The whole process is real-time displayed on the screen; meanwhile alarm messages are given to the operator when interference between milling cutter and workpiece occurs. The simulation result is displayed using a visual realism technique, from which gross programming errors can be checked with ease. The function of each module in this simulation system is discussed in detail using an example. This system simulates NC milling processes efficiently on a microcomputer platform.